Block copolymer composition and methods relating thereto

ABSTRACT

A copolymer composition is provided including a block copolymer having a poly(acrylate) block and a poly(silyl acrylate) block; wherein the block copolymer exhibits a number average molecular weight, M N , of 1 to 1,000 kg/mol; and, wherein the block copolymer exhibits a polydispersity, PD, of 1 to 2. Also provided are substrates treated with the copolymer composition.

The present invention relates to the field of self assembling blockcopolymers. In particular, the present invention is directed to aspecific copolymer composition including a block copolymer having apoly(acrylate) block and a poly(silyl acrylate) block.

Some block copolymers, consisting of two or more distinct homopolymersjoined end to end, are known self-assemble into periodic micro domainshaving typical dimensions of 10 nanometers to 50 nanometers (nm). Thepossibility of using such micro domains to pattern surfaces hasattracted increasing interest because of the expense and difficulty ofpatterning in nanoscale dimensions (especially sub-45 nm) using opticallithography.

Controlling the lateral placement of the block copolymer micro domainson the substrates continues to be a challenge, however. This problem hasbeen previously addressed using lithographically predefined topographicand/or chemical patterning of the substrate. Previous studies havedemonstrated that self assembled block copolymer micro domains in formof lamellae can be directed to follow chemical patterning of thesubstrate, yielding periodicities close to those of the chemicalprepatterns. Other studies have shown that by controlling the surfacewetting properties of the block copolymer on the bottom and side wallsof a topographic prepattern, the lamellae can be directed to follow thetopographic prepattern. The lamellae formed line/space patterns ofsmaller dimensions than the substrate prepattern, subdividing thetopographic prepattern into a higher frequency line pattern; that is, aline pattern having a smaller pitch. One limitation of block copolymerpatterning is the propensity of the patterns to form everywhere on thepre-pattern surface, for topographic and/or chemical guidingprepatterns.

The ability to shrink the size of various features on a given substrate(e.g., gates in field effect transistors) is currently limited by thewavelength of light used to expose photoresists (i.e., 193 nm). Theselimitations create a significant challenge for the fabrication offeatures having a critical dimension (CD) of <50 nm. The use ofconventional block copolymers present difficulties in orientationcontrol and long range ordering during the self assembly process.Moreover, such block copolymers frequently provide inadequate etchresistance for subsequent processing steps.

Takenaka, et al.¹ investigated the use of diblock copolymer for directedself assembly. Specifically, Takenaka, et al. demonstrated the directedself assembly down to sub 10 nm half pitch using apoly(styrene)-b-poly(dimethyl siloxane) diblock copolymer with amolecular weight of 15.8 kg/mol; a heterogeneity index of 1.03; and, apoly(styrene) volume fraction of 0.74 poly(styrene); wherein the diblockcopolymer film was annealed in vacuum at 170° C. for 24 hours.¹Takenaka, et al, Formation of long-range stripe patterns with sub-10-nmhalf-pitch from directed self-assembly of block copolymer, JOURNAL OFPOLYMER SCIENCE: PART B, Polymer Physics, vol. 48, pp. 2297-2301 (2010).

Notwithstanding, there remains a need for new copolymer compositions foruse in patterning substrates. In particular, there remains a need fornew copolymer compositions that enable patterning on intermediate lengthscales (e.g., 20 to 40 nm) and that preferably exhibit a fast annealingprofile with low defect formation.

The present invention provides a copolymer composition, comprising: ablock copolymer having a poly(acrylate) block and a poly(silyl acrylate)block; and, an antioxidant; wherein the block copolymer exhibits anumber average molecular weight, M_(N), of 1 to 1,000 kg/mol; whereinthe copolymer composition contains ≧2 wt % antioxidant (based on theweight of the block copolymer); and, wherein the block copolymerexhibits a polydispersity, PD, of 1 to 2.

The present invention provides a method comprising: providing asubstrate; providing a copolymer composition of the present invention;applying a film of the copolymer composition to the substrate;optionally, baking the film; annealing the film, leaving a pattern ofpoly(acrylate) domains and poly(silyl acrylate) domains; treating theannealed film to remove the poly(acrylate) domains from the annealedfilm and to convert the poly(silyl acrylate) domains in the annealedfilm to SiO_(x).

The present invention provides a copolymer composition, comprising: ablock copolymer having a poly(acrylate) block and a poly(silyl acrylate)block; wherein the block copolymer exhibits a number average molecularweight, M_(N), of 1 to 1,000 kg/mol; wherein the block copolymerexhibits a polydispersity, PD, of 1 to 2; and, wherein the blockcopolymer contains ≦75 wt % of a poly(methylmethacrylate)-block-poly((trimethylsilyl)methyl methacrylate) diblockcopolymer.

The present invention provides a copolymer composition, comprising: ablock copolymer having a poly(acrylate) block and a poly(silyl acrylate)block; wherein the block copolymer exhibits a number average molecularweight, M_(N), of 1 to 1,000 kg/mol; wherein the block copolymerexhibits a polydispersity, PD, of 1 to 2; and, wherein the blockcopolymer contains ≦0.001 wt % of a poly(methylmethacrylate)-block-poly((trimethylsilyl)methyl methacrylate) diblockcopolymer.

DETAILED DESCRIPTION

When applied to the surface of a substrate, the copolymer composition ofthe present invention exhibits an improved capability to anneal at agiven processing temperature to a low defect structure compared to thatobtained using a conventional silicon containing polymers, such asPS-b-PDMS. Moreover, the incorporation of an inorganic moiety in thepoly(silyl acrylate) domain of the copolymer composition of the presentinvention is convertible to an etch resistant species (e.g., a mask)upon processing of the deposited copolymer composition to remove theorganic components. The copolymer composition of the present inventionprovides significant value for enabling thermal processing in directedself assembly applications used to form periodic nanostructures, such asline/space patterns on silicon containing substrates, in, for example,the 20-40 nm range.

The term “PAcr-b-PSiAcr block copolymer” used herein and in the appendedclaims is short hand for a poly(acrylate)-block-poly(silyl acrylate);wherein the poly(acrylate) block includes residues from at least one ofan acrylate monomer, a deuterated acrylate monomer, an acrylate blockmodifying monomer and a deuterated acrylate block modifying monomer;and, wherein the poly(silyl acrylate) block includes residues from atleast one of a silyl acrylate monomer, a deuterated silyl acrylatemonomer, a silyl acrylate block modifying monomer and a deuterated silylacrylate block modifying monomer.

The term “deuterated acrylate monomer” used herein and in the appendedclaims is an acrylate monomer in which at least one hydrogen has beenreplaced with deuterium.

The term “deuterated acrylate block modifying monomer” used herein andin the appended claims is an acrylate modifying monomer in which atleast one hydrogen has been replaced with deuterium.

The term “deuterated silyl acrylate monomer” used herein and in theappended claims is a silyl acrylate monomer in which at least onehydrogen has been replaced with deuterium.

The term “deuterated silyl acrylate block modifying monomer” used hereinand in the appended claims is a silyl acrylate modifying monomer inwhich at least one hydrogen has been replaced with deuterium.

The terms “(trimethylsilyl)methyl methacrylate” and “TMSMMA” used hereinand in the appended claims refers to a monomer having the followingmolecular structure:

The term “M_(N-BCP)” used herein and in the appended claims in referenceto a block copolymer of the present invention is the number averagemolecular weight of the block copolymer determined according to themethod used herein in the Examples.

The term “M_(W-BCP)” used herein and in the appended claims in referenceto a block copolymer of the present invention is the weight averagemolecular weight of the block copolymer determined according to themethod used herein in the Examples.

The term “PD_(BCP)” used herein and in the appended claims in referenceto a block copolymer of the present invention is the polydispersity ofthe block copolymer determined according to the following equation:

${PD}_{BCP} = {\frac{M_{W - {BCP}}}{M_{N - {BCP}}}.}$

The term “Wf_(PAcr)” used herein and in the appended claims in referenceto a block copolymer of the present invention is the weight percent ofthe poly(acrylate) block in the block copolymer.

The term “Wf_(PSiAcr)” used herein and in the appended claims inreference to a block copolymer of the present invention is the weightpercent of the poly(silyl acrylate) block in the block copolymer.

Block copolymers are polymers that are synthesized from two or moredifferent monomers and exhibit two or more polymeric chain segments thatare chemically different, but yet, are covalently bound to one another.Diblock copolymers are a special class of block copolymers derived fromtwo different monomers (e.g., A and B) and having a structure comprisinga polymeric block of A residues covalently bound to a polymeric block ofB residues (e.g., AAAAA-BBBBB).

The block copolymer used in the copolymer composition of the presentinvention include block copolymers having at least two different blocks;wherein one of the blocks is a poly(acrylate) block and one of theblocks is a poly(silyl acrylate) block. The block copolymers used in thecopolymer composition of the present invention optionally contain one ormore other blocks (e.g., a triblock copolymer).

Preferably, the block copolymer used in the copolymer composition of thepresent invention is a PAcr-b-PSiAcr diblock copolymer comprisingdomains of poly(acrylate) block and poly(silyl acrylate) block; whereinthe block copolymer exhibits a film pitch, L₀, of 10 to 100 nm(preferably 14 to 60 nm; most preferably 20 to 40 nm) when deposited ona substrate under the conditions set forth herein in the Examples.

Preferably, the block copolymer used in the copolymer composition of thepresent invention is a PAcr-b-PSiAcr diblock copolymer comprisingdomains of poly(acrylate) and poly(silyl acrylate); wherein the blockcopolymer exhibits a number average molecular weight, M_(N-BCP), of 1 to1,000 kg/mol (preferably 10 to 500 kg/mol; more preferably 15 to 300kg/mol; still more preferably 15 to 100 kg/mol; most preferably 20 to 60kg/mol); and, wherein the block copolymer exhibits a polydispersity,PD_(BCP), of 1 to 3 (preferably 1 to 2; most preferably 1 to 1.2).

Preferably, the block copolymer used in the copolymer composition of thepresent invention is a PAcr-b-PSiAcr diblock copolymer comprisingdomains of poly(acrylate) and poly(silyl acrylate); wherein the diblockcopolymer has a poly(acrylate) weight fraction, Wf_(PAcr), of 0.69 to0.83 (preferably 0.69 to 0.80; most preferably 0.70 to 0.75); andwherein the diblock copolymer has a number average molecular weight,M_(N), of 10 to 1,000 kg/mol (preferably 15 to 200 kg/mol; morepreferably 15 to 100 kg/mol; most preferably 20 to 60 kg/mol). Diblockcopolymers of the present invention having a Wf_(PAcr) of 0.69 to 0.83and a number average molecular weight, M_(N), of 10 to 1,000 kg/mol tendto exhibit cylindrical poly(silyl acrylate) domains that microphaseseparate from the poly(acrylate) domains. Given the teachings providedherein, one of ordinary skill in the art will be able to deposit acopolymer composition of the present invention containing suchPAcr-b-PSiAcr diblock copolymers, wherein cylindrical poly(silylacrylate) domains in the deposited copolymer composition will selfassemble to orient themselves with their axes of symmetry parallel tothe surface of the substrate, perpendicular to the surface of thesubstrate or a combination of parallel and perpendicular to the surfaceof the substrate, through the selection and control of the filmdeposition conditions, for example: (a) the substrate's surface energy(i.e., by pretreating the surface of the substrate with an interposingmaterial), (b) the thickness of the film of copolymer compositiondeposited, (c) the bake profile of the deposited copolymer composition(i.e., bake temperature and bake time) and (d) the anneal profile of thedeposited copolymer composition (i.e., anneal temperature and annealtime).

Preferably, the block copolymer of the present invention is aPAcr-b-PSiAcr diblock copolymer comprising domains of poly(acrylate) andpoly(silyl acrylate); wherein the diblock copolymer has a poly(acrylate)weight fraction, Wf_(PAcr), of 0.39 to <0.69 (preferably 0.44 to 0.64;most preferably 0.49 to 0.59); and wherein the diblock copolymer has anumber average molecular weight, M_(N), of 10 to 1,000 kg/mol(preferably 15 to 200 kg/mol; more preferably 15 to 100 kg/mol; mostpreferably 20 to 60 kg/mol). Diblock copolymers of the present inventionhaving a Wf_(PAcr) of 0.39 to <0.69 and a number average molecularweight, M_(N), of 10 to 1,000 kg/mol tend to exhibit microphaseseparated poly(acrylate) and poly(silyl acrylate) lamellar domains.Given the teachings provided herein, one of ordinary skill in the artwill be able to deposit a copolymer composition of the present inventioncontaining such PAcr-b-PSiAcr diblock copolymers, wherein lamellardomains in the deposited copolymer composition will self assemble toorient themselves with their axes of symmetry parallel to the surface ofthe substrate, perpendicular to the surface of the substrate or acombination of parallel and perpendicular to the surface of thesubstrate, through the selection and control of the film depositionconditions, for example: (a) the substrate's surface energy (i.e., bypretreating the surface of the substrate with an interposing material),(b) the thickness of the film of copolymer composition deposited, (c)the bake profile of the deposited copolymer composition (i.e., baketemperature and bake time) and (d) the anneal profile of the depositedcopolymer composition (i.e., anneal temperature and anneal time).

Preferably, the block copolymer used in the copolymer composition of thepresent invention is a PAcr-b-PSiAcr diblock copolymer comprisingdomains of poly(acrylate) and poly(silyl acrylate); wherein the diblockcopolymer has a poly(acrylate) weight fraction, Wf_(PAcr), of 0.23 to<0.39 (preferably 0.26 to 0.34; most preferably 0.27 to 0.30); andwherein the diblock copolymer has a number average molecular weight,M_(N), of 10 to 1,000 kg/mol (preferably 15 to 200 kg/mol; morepreferably 15 to 100 kg/mol; most preferably 20 to 60 kg/mol). Diblockcopolymers of the present invention having a Wf_(PAcr) of 0.23 to <0.39and a number average molecular weight, M_(N), of 10 to 1,000 kg/mol tendto exhibit cylindrical poly(acrylate) domains that microphase separatefrom the poly(silyl acrylate). Given the teachings provided herein, oneof ordinary skill in the art will be able to deposit a copolymercomposition of the present invention containing such PAcr-b-PSiAcrdiblock copolymers, wherein cylindrical poly(acrylate) domains in thedeposited copolymer composition will self assemble to orient themselveswith their axes of symmetry parallel to the surface of the substrate,perpendicular to the surface of the substrate or a combination ofparallel and perpendicular to the surface of the substrate, through theselection and control of the film deposition conditions, for example:(a) the substrate's surface energy (i.e., by pretreating the surface ofthe substrate with an interposing material), (b) the thickness of thefilm of copolymer composition deposited, (c) the bake profile of thedeposited copolymer composition (i.e., bake temperature and bake time)and (d) the anneal profile of the deposited copolymer composition (i.e.,anneal temperature and anneal time).

Preferably, the poly(acrylate)-b-poly(silyl acrylate) block copolymershave a poly(acrylate) block; wherein the poly(acrylate) block includesresidues from at least one of an acrylate monomer, a deuterated acrylatemonomer, an acrylate block modifying monomer and a deuterated acrylateblock modifying monomer; and, wherein the poly(acrylate) blockincludes >75 wt % (more preferably, >90 wt %; most preferably, >95 wt %)of acrylate monomer derived units.

Preferably, the acrylate monomer is selected from the group consistingof aryl (alkyl)acrylate (e.g., phenyl acrylate, phenyl methacrylate);alkyl (alkyl)acrylate (e.g., methyl acrylate, methyl methacrylate);halogenated aryl (alkyl)acrylate (e.g., chlorophenyl acrylate,chlorophenyl methacrylate); halogenated alkyl (alkyl)acrylate (e.g.,fluoropropyl acrylate, fluoropropyl methacrylate) and, combinationsthereof. More preferably, the acrylate monomer is selected from thegroup consisting of C₆₋₁₄ aryl (C₁₋₅ alkyl)acrylate; C₁₋₅ alkyl (C₁₋₅alkyl)acrylate. Still more preferably, the acrylate monomer is selectedfrom the group consisting of butyl (meth)acrylate, propyl(meth)acrylate), ethyl (meth)acrylate, methyl (meth)acrylate. Mostpreferably, the acrylate monomer is methyl methacrylate.

Preferably, the deuterated acrylate monomer is selected from the groupconsisting of deuterated aryl (alkyl)acrylate (e.g., deuterated phenylacrylate, deuterated phenyl methacrylate); deuterated alkyl(alkyl)acrylate (e.g., deuterated methyl acrylate, deuterated methylmethacrylate); deuterated halogenated aryl (alkyl)acrylate (e.g.,deuterated chlorophenyl acrylate, deuterated chlorophenyl methacrylate);deuterated halogenated alkyl (alkyl)acrylate (e.g., deuteratedfluoropropyl acrylate, deuterated fluoropropyl methacrylate) and,combinations thereof. More preferably, the deuterated acrylate monomeris selected from the group consisting of deuterated C₆₋₁₄ aryl (C₁₋₅alkyl)acrylate; deuterated C₁₋₅ alkyl (C₁₋₅ alkyl)acrylate. Still morepreferably, the deuterated acrylate monomer is selected from the groupconsisting of deuterated butyl (meth)acrylate, deuterated propyl(meth)acrylate), deuterated ethyl (meth)acrylate, deuterated methyl(meth)acrylate. Most preferably, the deuterated acrylate monomer isdeuterated methyl methacrylate.

Preferably, the acrylate block modifying monomer is selected from thegroup consisting of an alkene and a cycloalkene. More preferably, theacrylate block modifying monomer is selected from a C₁₋₅ alkene and aC₃₋₇ cycloalkene. Most preferably, the acrylate block modifying monomeris ethylene.

Preferably, the deuterated acrylate block modifying monomer is selectedfrom the group consisting of a deuterated alkene and a deuteratedcycloalkene. More preferably, the deuterated acrylate block modifyingmonomer is selected from a deuterated C₁₋₅ alkene and deuterated a C₃₋₇cycloalkene. Most preferably, the deuterated acrylate block modifyingmonomer is deuterated ethylene.

Preferably, the poly(acrylate)-b-poly(silyl acrylate) block copolymershave a poly(silyl acrylate) block; wherein the poly(silyl acrylate)block includes residues from at least one of a silyl acrylate monomer, adeuterated silyl acrylate monomer, a silyl acrylate block modifyingmonomer and a deuterated silyl acrylate block modifying monomer; and,wherein the poly(silyl acrylate) block includes >75 wt % (morepreferably, >90 wt %; most preferably, >95 wt %) of silyl acrylatemonomer derived units.

Preferably, the silyl acrylate monomer is according to the followingformula(R¹(R²)(R³)Si)_(r)R⁴ _(x)OOCC(R⁵)═CR⁶ ₂wherein each R¹, R² and R³ is independently selected from the groupconsisting of a C₁₋₁₈ alkyl group, a halogenated C₁₋₁₈ alkyl group, asilylated C₁₋₁₈ alkyl group, a silylated halogenated C₁₋₁₈ alkyl group,an oxy C₁₋₁₈ alkyl group, an oxy silylated C₁₋₁₈ alkyl group, an oxysilylated halogenated C₁₋₁₈ alkyl group, a C₆₋₁₄ aryl group, ahalogenated C₆₋₁₄ aryl group, an oxy C₆₋₁₄ aryl group, a silylated C₆₋₁₄aryl group, an oxy silylated C₆₋₁₄ aryl group, an oxy silylatedhalogenated C₆₋₁₄ aryl group, a C₁₋₁₈ arylalkyl group, a halogenatedC₁₋₁₈ arylalkyl group, an oxy C₁₋₁₈ arylalkyl group, a silylated C₁₋₁₈arylalkyl group, a silylated halogenated C₁₋₁₈ arylalkyl group, an oxysilylated C₁₋₁₈ arylalkyl group, an oxy silylated halogenated C₁₋₁₈arylalkyl group, a C₆₋₁₄ alkylaryl group, a halogenated C₆₋₁₄ alkylarylgroup, an oxy C₆₋₁₄ alkylaryl group, a silylated C₆₋₁₄ alkylaryl group,an oxy silylated C₆₋₁₄ alkylaryl group and an oxy silylated halogenatedC₆₋₁₄ alkylaryl group (preferably, a C₁₋₆ alkyl group, a silylated C₁₋₆alkyl group, an oxy C₁₋₆ alkyl group, an oxy silylated C₁₋₆ alkyl group,a C₆₋₁₀ aryl group, an oxy C₆₋₁₀ aryl group, a silylated C₆₋₁₀ arylgroup, an oxy silylated C₆₋₁₀ aryl group, a C₁₋₁₀ arylalkyl group, anoxy C₁₋₁₀ arylalkyl group, a silylated C₁₋₁₀ arylalkyl group, an oxysilylated C₁₋₁₀ arylalkyl group, a C₆₋₁₀ alkylaryl group, an oxy C₆₋₁₀alkylaryl group, a silylated C₆₋₁₀ alkylaryl group and an oxy silylatedC₆₋₁₀ alkylaryl group; more preferably, a C₁₋₃ alkyl group; mostpreferably, a methyl group); wherein r is selected from the groupconsisting of 0, 1, 2 and 3 (preferably, 1, 2 and 3; more preferably, ris 1); wherein R⁴ is selected from the group consisting of a C₁₋₁₀alkyl, a halogenated C₁₋₁₀ alkyl group, a silylated C₁₋₁₀ alkyl group, asilylated halogenated C₁₋₁₀ alkyl group, an oxy silylated C₁₋₁₀ alkylgroup and a halogenated oxy silylated C₁₋₁₀ alkyl group (preferably, aC₁₋₃ alkyl group and a halogenated C₁₋₃ alkyl group; more preferably, aC₁₋₃ alkyl group; most preferably a methyl group); wherein x is selectedfrom the group consisting of 0 and 1 (preferably, x is 1); wherein R⁵ isselected from the group consisting of a hydrogen, a halogen, a C₁₋₃alkyl group, a silylated C₁₋₃ alkyl group and a halogenated C₁₋₃ alkylgroup (preferably, a hydrogen and a methyl group; more preferably, amethyl group); wherein each R⁶ is independently selected from ahydrogen, a halogen, a silyl methyl group, a methyl group and ahalogenated methyl group (preferably, a hydrogen and a methyl group;more preferably, a hydrogen); and, wherein the silyl acrylate monomerincludes at least one Si atom. More preferably, the silyl acrylatemonomer is selected from the group consisting of (trimethylsilyl)methyl(meth)acrylate; (triethylsilyl)methyl (meth)acrylate;(tripropylsilyl)methyl (meth)acrylate; (triisopropylsilyl)methyl(meth)acrylate; (tributylsilyl)methyl (meth)acrylate;(tri-sec-butylsilyl)methyl (meth)acrylate; (triisobutylsilyl)methyl(meth)acrylate; (sec-butylmethylsilyl)methyl (meth)acrylate;(sec-butyldimethylsilyl)methyl (meth)acrylate;(dimethylpropylsilyl)methyl (meth)acrylate;(monomethyldipropylsilyl)methyl (meth)acrylate;(methylethylpropylsilyl)methyl (meth)acrylate; bis(trimethylsilyl)methyl(meth)acrylate; tris(trimethylsilyl)methyl (meth)acrylate;(pentamethyldisilyl)methyl (meth)acrylate; tris(trimethylsiloxy)methyl(meth)acrylate; tris(trimethylsiloxy)propyl (meth)acrylate);(pentamethyldisiloxy)methyl (meth)acrylate; (pentamethyldisiloxy)propyl(meth)acrylate; (trimethoxysilyl)propyl (meth)acrylate; and,(triethoxysilyl)propyl (meth)acrylate. Most preferably, the silylacrylate monomer is (trimethylsilyl)methyl methacrylate.

Preferably, the deuterated silyl acrylate monomer is according to thefollowing formula(R⁷(R⁸)(R⁹)Si)_(t)R¹⁰ _(y)OOCC(R¹¹)═CR¹² ₂wherein each R⁷, R⁸ and R⁹ is independently selected from a C₁₋₁₈ alkylgroup, a halogenated C₁₋₁₈ alkyl group, a silylated C₁₋₁₈ alkyl group, asilylated halogenated C₁₋₁₈ alkyl group, an oxy C₁₋₁₈ alkyl group, anoxy silylated C₁₋₁₈ alkyl group, an oxy silylated halogenated C₁₋₁₈alkyl group, a C₆₋₁₄ aryl group, a halogenated C₆₋₁₄ aryl group, an oxyC₆₋₁₄ aryl group, a silylated C₆₋₁₄ aryl group, an oxy silylated C₆₋₁₄aryl group, an oxy silylated halogenated C₆₋₁₄ aryl group, a C₁₋₁₈arylalkyl group, a halogenated C₁₋₁₈ arylalkyl group, an oxy C₁₋₁₈arylalkyl group, a silylated C₁₋₁₈ arylalkyl group, a silylatedhalogenated C₁₋₁₈ arylalkyl group, an oxy silylated C₁₋₁₈ arylalkylgroup, an oxy silylated halogenated C₁₋₁₈ arylalkyl group, a C₆₋₁₄alkylaryl group, a halogenated C₆₋₁₄ alkylaryl group, an oxy C₆₋₁₄alkylaryl group, a silylated C₆₋₁₄ alkylaryl group, an oxy silylatedC₆₋₁₄ alkylaryl group, an oxy silylated halogenated C₆₋₁₄ alkylarylgroup, a deuterated C₁₋₁₈ alkyl group, a deuterated halogenated C₁₋₁₈alkyl group, a deuterated silylated C₁₋₁₈ alkyl group, a deuteratedsilylated halogenated C₁₋₁₈ alkyl group, a deuterated oxy C₁₋₁₈ alkylgroup, a deuterated oxy silylated C₁₋₁₈ alkyl group, a deuterated oxysilylated halogenated C₁₋₁₈ alkyl group, a deuterated C₆₋₁₄ aryl group,a deuterated halogenated C₆₋₁₄ aryl group, a deuterated oxy C₆₋₁₄ arylgroup, a deuterated silylated C₆₋₁₄ aryl group, a deuterated oxysilylated C₆₋₁₄ aryl group, a deuterated oxy silylated halogenated C₆₋₁₄aryl group, a deuterated C₁₋₁₈ arylalkyl group, a deuterated halogenatedC₁₋₁₈ arylalkyl group, a deuterated oxy C₁₋₁₈ arylalkyl group, adeuterated silylated C₁₋₁₈ arylalkyl group, a deuterated silylatedhalogenated C₁₋₁₈ arylalkyl group, a deuterated oxy silylated C₁₋₁₈arylalkyl group, a deuterated oxy silylated halogenated C₁₋₁₈ arylalkylgroup, a deuterated C₆₋₁₄ alkylaryl group, a deuterated halogenatedC₆₋₁₄ alkylaryl group, a deuterated oxy C₆₋₁₄ alkylaryl group, adeuterated silylated C₆₋₁₄ alkylaryl group, a deuterated oxy silylatedC₆₋₁₄ alkylaryl group and a deuterated oxy silylated halogenated C₆₋₁₄alkylaryl group (preferably, a C₁₋₆ alkyl group, a silylated C₁₋₆ alkylgroup, an oxy C₁₋₆ alkyl group, an oxy silylated C₁₋₆ alkyl group, aC₆₋₁₀ aryl group, an oxy C₆₋₁₀ aryl group, a silylated C₆₋₁₀ aryl group,an oxy silylated C₆₋₁₀ aryl group, a C₁₋₁₀ arylalkyl group, an oxy C₁₋₁₀arylalkyl group, a silylated C₁₋₁₀ arylalkyl group, an oxy silylatedC₁₋₁₀ arylalkyl group, a C₆₋₁₀ alkylaryl group, an oxy C₆₋₁₀ alkylarylgroup, a silylated C₆₋₁₀ alkylaryl group, an oxy silylated C₆₋₁₀alkylaryl group, a deuterated C₁₋₆ alkyl group, a deuterated silylatedC₁₋₆ alkyl group, a deuterated oxy C₁₋₆ alkyl group, a deuterated oxysilylated C₁₋₆ alkyl group, a deuterated C₆₋₁₀ aryl group, a deuteratedoxy C₆₋₁₀ aryl group, a deuterated silylated C₆₋₁₀ aryl group, adeuterated oxy silylated C₆₋₁₀ aryl group, a deuterated C₁₋₁₀ arylalkylgroup, a deuterated oxy C₁₋₁₀ arylalkyl group, a deuterated silylatedC₁₋₁₀ arylalkyl group, a deuterated oxy silylated C₁₋₁₀ arylalkyl group,a deuterated C₆₋₁₀ alkylaryl group, a deuterated oxy C₆₋₁₀ alkylarylgroup, a deuterated silylated C₆₋₁₀ alkylaryl group and a deuterated oxysilylated C₆₋₁₀ alkylaryl group; more preferably, a C₁₋₃ alkyl group anda deuterated C₁₋₃ alkyl group; most preferably, a methyl group and adeuterated methyl group); wherein t is selected from the groupconsisting of 0, 1, 2 and 3 (preferably, 1, 2 and 3; more preferably, tis 1); wherein R¹⁰ is selected from the group consisting of a C₁₋₁₀alkyl, a halogenated C₁₋₁₀ alkyl group, a silylated C₁₋₁₀ alkyl group, asilylated halogenated C₁₋₁₀ alkyl group, an oxy silylated C₁₋₁₀ alkylgroup, a halogenated oxy silylated C₁₋₁₀ alkyl group, a deuterated C₁₋₁₀alkyl, a deuterated halogenated C₁₋₁₀ alkyl group, a deuteratedsilylated C₁₋₁₀ alkyl group, a deuterated silylated halogenated C₁₋₁₀alkyl group, a deuterated oxy silylated C₁₋₁₀ alkyl group and adeuterated halogenated oxy silylated C₁₋₁₀ alkyl group (preferably, aC₁₋₃ alkyl group and a deuterated C₁₋₃ alkyl group; more preferably, aC₁₋₃ alkyl group; most preferably a methyl group); wherein y is 0 or 1(preferably, y is 1); wherein R¹¹ is selected from the group consistingof a hydrogen, a deuterium, a halogen, a C₁₋₃ alkyl group, a deuteratedC₁₋₃ alkyl group, a silylated C₁₋₃ alkyl group, a deuterated silylatedC₁₋₃ alkyl group, a halogenated C₁₋₃ alkyl group and a deuteratedhalogenated C₁₋₃ alkyl group (preferably, a hydrogen, a deuterium, amethyl group and a deuterated methyl group; more preferably, a methylgroup); wherein each R¹² is independently selected from a hydrogen, adeuterium, a halogen, a silyl methyl group, a deuterated silyl methylgroup, a methyl group, a deuterated methyl group, a halogenated methylgroup and a deuterated halogenated methyl group (preferably, a hydrogen,a deuterium, a methyl group and a deuterated methyl group; morepreferably, a hydrogen); wherein the deuterated silyl acrylate monomercontains at least one Si atom; and, wherein the deuterated silylacrylate monomer contains at least one deuterium. More preferably, thedeuterated silyl acrylate monomer is selected from the group consistingof deuterated (trimethylsilyl)methyl (meth)acrylate; deuterated(triethylsilyl)methyl (meth)acrylate; deuterated (tripropylsilyl)methyl(meth)acrylate; deuterated (triisopropylsilyl)methyl (meth)acrylate;deuterated (tributylsilyl)methyl (meth)acrylate; deuterated(tri-sec-butylsilyl)methyl (meth)acrylate; deuterated(triisobutylsilyl)methyl (meth)acrylate; deuterated(sec-butylmethylsilyl)methyl (meth)acrylate; deuterated(sec-butyldimethylsilyl)methyl (meth)acrylate; deuterated(dimethylpropylsilyl)methyl (meth)acrylate; deuterated(monomethyldipropylsilyl)methyl (meth)acrylate; deuterated(methylethylpropylsilyl)methyl (meth)acrylate; deuteratedbis(trimethylsilyl)methyl (meth)acrylate; deuteratedtris(trimethylsilyl)methyl (meth)acrylate; deuterated(pentamethyldisilyl)methyl (meth)acrylate; deuteratedtris(trimethylsiloxy)methyl (meth)acrylate; deuteratedtris(trimethylsiloxy)propyl (meth)acrylate); deuterated(pentamethyldisiloxy)methyl (meth)acrylate; deuterated(pentamethyldisoloxy)propyl (meth)acrylate; deuterated(trimethoxysilyl)propyl (meth)acrylate; and, deuterated(triethoxysilyl)propyl (meth)acrylate. Most preferably, the deuteratedsilyl acrylate monomer is deuterated (trimethylsilyl)methylmethacrylate.

Preferably, the silyl acrylate block modifying monomer is selected fromthe group consisting of an alkene and a cycloalkene. More preferably,the silyl acrylate block modifying monomer is selected from a C₁₋₅alkene and a C₃₋₇ cycloalkene. Most preferably, the silyl acrylate blockmodifying monomer is ethylene.

Preferably, the deuterated silyl acrylate block modifying monomer isselected from the group consisting of a deuterated alkene and adeuterated cycloalkene. More preferably, the deuterated silyl acrylateblock modifying monomer is selected from a deuterated C₁₋₅ alkene anddeuterated a C₃₋₇ cycloalkene. Most preferably, the deuterated silylacrylate block modifying monomer is deuterated ethylene.

Preferably, the copolymer composition of the present invention contains≧2 wt % antioxidant (based on the weight of the PAcr-b-PSiAcr blockcopolymer). More preferably, the copolymer composition contains 2 to 30wt % antioxidant (based on the weight of the PAcr-b-PSiAcr blockcopolymer). Still more preferably, the copolymer composition contains 5to 30 wt % antioxidant (based on the weight of the PAcr-b-PSiAcr blockcopolymer). Still more preferably, the copolymer composition contains 10to 25 wt % antioxidant (based on the weight of the PAcr-b-PSiAcr blockcopolymer). Most preferably, the copolymer composition contains 15 to 25wt % antioxidant (based on the weight of the PAcr-b-PSiAcr blockcopolymer).

Antioxidant contained in the copolymer composition of the presentinvention can be selected from primary antioxidants and secondaryantioxidants. Preferably, the antioxidant is selected from the groupconsisting of: antioxidants containing at least one (preferably at leasttwo; more preferably at least three; most preferably three to four)2,6-di-tert-butylphenol moiety; antioxidants containing at least one(preferably at least two; more preferably at least three; mostpreferably three to four) moiety according to the formula

antioxidants containing at least one (preferably at least two; mostpreferably two) moiety according to the formula

antioxidants containing at least one (preferably at least two; mostpreferably two) moiety according to the formula

mixtures thereof. More preferably, the antioxidant is selected from thegroup consisting of:

mixtures thereof. Still more preferably, the antioxidant is selectedfrom the group consisting of

and mixtures of

and one or more other antioxidants. Most preferably, the antioxidant is

Preferably, the antioxidant (or mixture of antioxidants) contained inthe copolymer composition of the present invention has an averagemolecular weight of ≧358 g/mol. More preferably, the antioxidant (ormixture of antioxidants) contained in the copolymer composition of thepresent invention has an average molecular weight of ≧600 g/mol. Mostpreferably, the antioxidant (or mixture of antioxidants) contained inthe copolymer composition of the present invention has an averagemolecular weight of ≧1,000 g/mol.

Preferably, the antioxidant (or mixture of antioxidants) contained inthe copolymer composition of the present invention has an averageboiling point temperature measured at 760 mm Hg (101.3 kPa) of >400° C.More preferably, the antioxidant (or mixture of antioxidants) containedin the copolymer composition of the present invention has an averageboiling point temperature measured at 760 mm Hg (101.3 kPa) of >500° C.Still more preferably, the antioxidant (or mixture of antioxidants)contained in the copolymer composition of the present invention has anaverage boiling point temperature measured at 760 mm Hg (101.3 kPa)of >700° C. Yet still more preferably, the antioxidant (or mixture ofantioxidants) contained in the copolymer composition of the presentinvention has an average boiling point temperature measured at 760 mm Hg(101.3 kPa) of >800° C. Most preferably, the antioxidant (or mixture ofantioxidants) contained in the copolymer composition of the presentinvention has an average boiling point temperature measured at 760 mm Hg(101.3 kPa) of >1,000° C.

The copolymer composition of the present invention optionally furthercomprises a solvent. Solvents include liquids that are able to dispersethe block copolymer into particles or aggregates having an averagehydrodynamic diameter of less than 50 nm as measured by dynamic lightscattering. Preferably, the solvent used is selected from propyleneglycol monomethyl ether acetate (PGMEA), ethoxyethyl propionate,anisole, ethyl lactate, 2-heptanone, cyclohexanone, amyl acetate,γ-butyrolactone (GBL), n-methylpyrrolidone (NMP) and toluene. Morepreferably, the solvent used is selected from propylene glycolmonomethyl ether acetate (PGMEA) and toluene. Most preferably, thesolvent used is toluene.

The copolymer composition of the present invention optionally furthercomprises an additive. Additives include additional polymers (includinghomopolymers and random copolymers); surfactants; photoacid generators;thermal acid generators; quenchers; hardeners; adhesion promoters;dissolution rate modifiers; photocuring agents; photosensitizers; acidamplifiers; plasticizers; orientation control agents; and cross linkingagents. Preferred additives for use in the copolymer composition of thepresent invention include surfactants.

The method of the present invention preferably comprises: providing asubstrate; providing a copolymer composition of the present invention;applying a film of the copolymer composition to the substrate;optionally, baking the film; annealing the film, leaving a pattern ofpoly(acrylate) domains and poly(silyl acrylate) domains; treating theannealed film to remove the poly(acrylate) domains from the annealedfilm and to convert the poly(silyl acrylate) domains in the annealedfilm to SiO_(x).

Substrates used in the method of the present invention include anysubstrate having a surface that can be coated with the copolymercomposition of the present invention. Preferred substrates includelayered substrates. Preferred substrates include silicon containingsubstrates (e.g., glass; silicon dioxide; silicon nitride; siliconoxynitride; silicon containing semiconductor substrates such as siliconwafers, silicon wafer fragments, silicon on insulator substrates,silicon on sapphire substrates, epitaxial layers of silicon on a basesemiconductor foundation, silicon-germanium substrates); plastic; metals(e.g., copper, ruthenium, gold, platinum, aluminum, titanium andalloys); titanium nitride; and non-silicon containing semiconductivesubstrates (e.g., non-silicon containing wafer fragments, non-siliconcontaining wafers, germanium, gallium arsenide and indium phosphide).Most preferred substrates are silicon containing substrates.

Optionally, the surface of the substrate to be coated with the copolymercomposition of the present invention is pretreated with an interposingmaterial before the copolymer composition of the present invention isapplied. Preferably, the pretreatment material acts like a tying layerinterposed between the surface of the substrate and the block copolymerin the copolymer composition of the present invention to enhance theadhesion between the block copolymer and the substrate. Preferably, theinterposing material forms a layer selected from an imaging layer and anorientation control layer.

Imaging layers suitable for use in the method of the present inventioninclude, for example, any type of material that can be patterned orselectively activated. Such materials include, for example, polymerbrushes and a self-assembled monolayers of silane and siloxanecompounds.

Orientation control layers suitable for use in the method of the presentinvention include neutral and non-neutral orientation control layers.That is, the orientation control layer can form an interface between thesurface of the substrate and the block copolymer in the copolymercomposition of the present invention that is preferentially wetted byone of poly(acrylate) domains or poly(silyl acrylate) domains—i.e., anon-neutral orientation control layer. A neutral orientation controllayer refers to a layer that forms an interface between the surface ofthe substrate and the block copolymer in the copolymer composition ofthe present invention that is equally wetted by both poly(acrylate) andpoly(silyl acrylate). Neutral orientation control layers preferablyinclude films prepared by casting a random copolymer that comprisesresidues of both acrylate monomers and silyl acrylate monomers (e.g.,poly(methyl methacrylate)-r-(trimethylsilyl)methyl methacrylate)-OH).

Preferably, the pretreatment of the substrate before depositing thecopolymer composition of the present invention is performed tofacilitate the guided self assembly of the block copolymer in thecopolymer composition. Specifically, the pretreatment can facilitate oneof the two conventional methods used for guided self assembly of blockcopolymer films, namely graphoepitaxy and chemical epitaxy. In thegraphoepitaxy, the surface of the substrate is prepatterned withtopographical features on the surface of substrate (e.g., trenches,holes) that operate to direct the self organization of the blocks in theblock copolymer.

In the chemical epitaxy, the surface of the substrate is treated with afilm that exhibits a compositional pattern, wherein the affinity betweenthe various parts of the compositional pattern is different forpoly(acrylate) and poly(silyl acrylate). This chemical affinitydifference operates to facilitate the directed self assembly of theblock copolymer in the copolymer composition.

Preferably, the interposing layer is formed on the substrate using amethod selected from spin coating, dip coating, roll coating, spraycoating and laminating (most preferably spin coating). After applicationof the interposing layer forming material onto the surface of thesubstrate, the material is optionally further processed to remove anyresidual solvent. Preferably, the interposing layer is baked at anelevated temperature (e.g., 70 to 340° C.) for at least 10 seconds to 5minutes to remove any residual solvent from the interposing layer.Preferably, the baked interposing layer is rinsed with a solvent capableof removing any residual unbound interposing layer material from thesurface of the substrate and then rebaked at an elevated temperature(e.g., 70 to 340° C.) for at least 10 seconds to 5 minutes to remove anyresidual solvent.

Applying a film of the copolymer composition of the present invention tothe substrate in the method of the present invention preferablycomprises depositing the copolymer composition onto the substrate usinga method selected from spin coating, dip coating, roll coating, spraycoating and laminating (most preferably spin coating). After applicationof the copolymer composition to the substrate, the deposited copolymercomposition is optionally further processed to remove any residualsolvent. Preferably, the deposited copolymer composition is baked at anelevated temperature (e.g., 70 to 340° C.) for at least 10 seconds to 5minutes to remove any residual solvent from the deposited film of thecopolymer composition.

Annealing of the deposited film can be done by any annealing technique,for example, thermal annealing, thermal gradient annealing and solventvapor annealing. Preferably, the film is annealed using a thermalannealing technique. More preferably, the deposited film is annealedusing a thermal annealing technique, wherein the deposited film isheated at a temperature of 200 to 340° C. (more preferably 200 to 300°C.; most preferably 225 to 300° C.) for a period of 0.5 minute to 2 days(more preferably 0.5 minute to 2 hours; still more preferably 0.5 minuteto 0.5 hour; most preferably 0.5 minute to 5 minutes). Preferably, thedeposited film is annealed using a thermal annealing technique under agaseous atmosphere, wherein the gaseous atmosphere is selected from anatmosphere containing ≧20 wt % oxygen and an atmosphere containing <20wt % oxygen. More preferably, the deposited film is thermally annealedunder a gaseous atmosphere, wherein the gaseous atmosphere is selectedfrom a gaseous nitrogen atmosphere and a gaseous argon atmosphere,wherein the gaseous atmosphere has an oxygen concentration of ≦150 ppm(more preferably, ≦10 ppm; still more preferably, ≦7.5 ppm; yet stillmore preferably, ≦6.5 ppm; most preferably, ≦5 ppm). Most preferably,the deposited film is thermally annealed under a gaseous nitrogenatmosphere having an oxygen concentration of ≦100 ppm (preferably, ≦7.5ppm; more preferably, ≦6.5 ppm; most preferably, ≦5 ppm).

In the method of the present invention, the annealed film is treated toremove the poly(acrylate) domains in the annealed film and to convertthe poly(silyl acrylate) domains in the annealed film to SiO_(x),providing a product film with a plurality of voids (i.e., trench shapedvoids perpendicular to the surface of the substrate; cylindrical holeswith axes of symmetry perpendicular to the surface of the substrate; aplurality of cylindrical SiO_(x) posts with axes of symmetryperpendicular to the surface of the substrate). The treatment comprises:exposing the film to conditions that exhibit differential reactivitytowards the poly(acrylate) in the film relative to the poly(silylacrylate) in the film, to facilitate removal of the poly(acrylate)domains from the annealed film and the conversion of the poly(silylacrylate) domains to SiO_(x). Preferably, the treatment comprises:optionally, exposing the annealed film to a halogen containing plasma(e.g., CF₄) to remove any wetting layer that formed on the surface ofthe annealed film; followed by exposing the annealed film to a reactiveplasma or a reactive ion etching atmosphere to remove the poly(acrylate)domains and to convert the poly(silyl acrylate) domains to SiO_(x). Mostpreferably, the treatment comprises: exposing the annealed film to ahalogen containing plasma to remove any wetting layer formed on theannealed film; and then exposing the annealed film to a reactive plasmaor a reactive ion etching atmosphere, wherein the atmosphere comprises aplasma composed of a low pressure ionized oxidizing gas (preferably O₂);wherein the poly(acrylate) domains in the annealed film is removed andthe poly(silyl acrylate) domains in the annealed film is converted toSiO_(x).

Some embodiments of the present invention will now be described indetail in the following Examples.

The following materials were passed through a column packed withactivated A-2 grade alumina before being used in the Examples herein,namely tetrahydrofuran (99.9% pure available from Aldrich), styrene(available from Aldrich), and cyclohexane (HPCL grade available fromFischer). The following materials were passed through a column packedwith basic alumina before being used in the Examples herein, namely1,1-diphenylethylene (available from Aldrich) and methyl methacrylate(MMA). All the other materials used in the Examples herein werecommercial materials that were used as received.

The film thicknesses reported in the Examples herein were measured usinga NanoSpec/AFT 2100 Film Thickness Measurement tool. The thickness ofthe films were determined from the interference of a white light passedthrough a diffraction grating. A standard program called “Polyimide onSilicon” was used to analyze the component wavelengths (380-780 nm) todetermine the film thickness. The thickness of the film of the depositedblock copolymer composition and the brush layer were measured togetheras one polymeric layer. The reported film thickness is the combinedthickness of the deposited block copolymer composition and the brushlayer.

The number average molecular weight, M_(N), and polydispersity valuesreported in the Examples were measured by gel permeation chromatography(GPC) on an Agilent 1100 series LC system equipped with an Agilent 1100series refractive index and MiniDAWN light scattering detector (WyattTechnology Co.). Samples were dissolved in HPCL grade THF at aconcentration of approximately 1 mg/mL and filtered through at 0.20 μmsyringe filter before injection through the two PLGel 300×7.5 mm Mixed Ccolumns (5 mm, Polymer Laboratories, Inc.). A flow rate of 1 mL/min andtemperature of 35° C. were maintained. The columns were calibrated withnarrow molecular weight PS standards (EasiCal PS-2, PolymerLaboratories, Inc.).

Proton nuclear magnetic resonance (¹H NMR) spectroscopy results referredto in the Examples was done on a Varian INOVA 400 MHz NMR spectrometer.Deuterated chloroform was used. A delay time of 10 seconds was used toensure complete relaxation of protons for quantitative integrations.Chemical shifts are reported relative to tetramethylsilane.

A PlasmaTherm 790i/reactive ion etch platform was used for all of thereactive ion etching steps mentioned in the Examples.

The film pitch, L₀, for the films reported in the Examples was measuredusing image analysis of the SEMS of the films with ImageJ, a publicdomain, JAVA based image processing program. Spatial calibration wasfirst carried out to convert distance in pixels in the image todistances in nanometers for a given SEM image. To measure the filmpitch, a line was drawn across and perpendicular to multiple SiO_(x)cylinders. The film pitch was calculated by dividing the length of thedrawn line by (n−1), wherein n is the number of SiO_(x) cylinderscrossed by the drawn line.

Example 1 Preparation of Hydroxyl-Terminated Polystyrene Brush

Into a 2 liter glass reactor under a nitrogen atmosphere was addedcyclohexane (1,500 g). Styrene (50.34 g) was then added to the reactorvia cannula. The contents of the reactor were then heated to 40° C.Sec-butyllithium (19.18 g) diluted in cyclohexane to a concentration of0.32 M was then rapidly added to the reactor via cannula, causing thereactor contents to turn yellow. The contents of the reactor werestirred for 30 minutes. The contents of the reactor were then cooled to30° C. Ethylene oxide (0.73 g) was then transferred into the reactor.The contents of the reactor were stirred for 15 minutes. Then a 20 mL ofa 1.4 M solution of HCl in methanol was added to the reactor. Thepolymer in the reactor was then isolated by precipitating intoisopropanol at a ratio of 500 mL of polymer solution to 1,250 mL ofisopropanol. The resulting precipitate was then filtered and driedovernight in a vacuum oven at 60° C., yielding 42 g of producthydroxyl-terminated polystyrene. The product hydroxyl-terminatedpolystyrene exhibited a number average molecular weight, M_(N), of 7.4kg/mol and a polydispersity, PD, of 1.07.

Comparative Example C1 Preparation of PS-b-PDMS Diblock Copolymer

Into a 500 mL 3-neck round bottom reactor under an argon atmosphere wasadded cyclohexane (90 mL) and styrene (18.4 g). The contents of thereactor were then warmed to 40° C. A 0.5 mL shot of a 1.4 M solution ofsec-butyllithium in cyclohexane was then rapidly added to the reactorvia cannula, causing the reactor contents to turn yellow-orange. Thereactor contents were allowed to stir for 30 minutes. A small portion ofthe reactor contents was then withdrawn from the reactor into a smallround bottomed flask containing anhydrous methanol for gel permeationchromatography analysis of the polystyrene block formed. Next2,2,5,5-tetramethyldisilafuran (337 mg) was added to the reactor. Slowlythe orange color began to fade. After 1 hour the contents of the reactorwere a slight yellow. Then a freshly sublimed hexamethylcyclotrisiloxane(10.1 g) was then transferred to the reactor via cannula. The reactorcontents were allowed to react for 1.5 hours until the reactor contentswere colorless. Then dry tetrahydrofuran (90 mL) was added to thereactor and the reaction was allowed to proceed for 3.25 hours.Chlorotrimethylsilane (1 mL) was then added to the reactor to quench thereaction. The product was isolated by precipitating into 500 mL ofmethanol and filtering. After washing with additional methanol, thepolymer was redissolved in 150 mL of methylene chloride, washed threetimes with deionized water and then reprecipitated into 500 mL ofmethanol. The polymer was then filtered and dried overnight in a vacuumoven at 70° C., yielding 22.1 g. The poly(styrene)-b-poly(dimethylsiloxane) block copolymer (“PS-b-PDMS”) product exhibited a numberaverage molecular weight, M_(N), of 35.8 kg/mol; a polydispersity, PD,of 1.01 and a 25.0 wt % PDMS content (as determined by ¹H NMR).

Example 2 Preparation PMMA-b-PTMSMMA Diblock Copolymer

Into a 500 mL 3-neck round bottom reactor under an argon atmosphere wasadded tetrahydrofuran (“THF”) (113 g). The THF was then cooled in thereactor to −78° C. The contents of the reactor were then titrated with a0.36 M solution of sec-butyllithium in cyclohexane until the contents ofthe reactor exhibited a persistent pale yellow color. The contents ofthe reactor were then warmed to, and maintained at, 30° C. until thecolor of the contents completely disappeared (approximately 10-15minutes). 1,1-diphenylethylene (0.116 g) diluted in cyclohexane (2.278g) was then transferred to the reactor via cannula. The contents of thereactor were then cooled to −78° C. Sec-butyllithium (6.15 g) dilutedwith cyclohexane to concentration of 0.065 M was then rapidly added tothe reactor via cannula, causing the reactor contents to turn a darkruby red. The reactor contents were allowed to stir for 10 minutes. Thenmethyl methacrylate (11.53 g) in cyclohexane (5.31 g) was transferred tothe reactor via cannula, causing the color of the reactor contents todisappear. The reactor contents exhibited a 21° C. temperature risewithin 1 minute of the addition of the methyl methacrylate to thereactor. The contents of the reactor then cooled back down to −78° C.and the reactor contents were stirred for an additional 60 minutes. Asmall portion of the reactor contents was then withdrawn for gelpermeation chromatography analysis of the polymethyl methacrylate(“PMMA”) block formed. (Trimethylsilyl) methyl methacrylate (“TMSMMA”)(4.52 g) diluted in cyclohexane (4.86 g) was then transferred into thereactor via cannula. Within 2 minutes of the addition of the TMSMMA tothe reactor, the reactor contents warmed to −69° C. before cooling backdown to −78° C. The reactor contents were stirred for an additional 2.5hours, after which the reaction was quenched by the addition ofanhydrous methanol to the reactor. The reactor contents were thenprecipitated into 1 liter of methanol. The product solids were collectedby vacuum filtration. After washing with additional methanol, thepolymer was redissolved in 150 mL of methylene chloride, washed twicewith deionized water and then reprecipitated into 1 liter of methanol.The polymer was then filtered and dried overnight in a vacuum oven at60° C., yielding 15.1 g. The product poly(methylmethacrylate)-b-poly(trimethylsilyl) methyl methacrylate block copolymer(“PMMA-b-PTMSMMA”) exhibited a weight average molecular weight, M_(W),of 31.4 kg/mol; a polydispersity, PD, of 1.21 and a 30 wt %poly(trimethylsilyl)methyl methacrylate content (as determined by ¹HNMR).

Example 3 Preparation PMMA-b-PTMSMMA Diblock Copolymer

Into a 500 mL 3-neck round bottom reactor under an argon atmosphere wasadded tetrahydrofuran (“THF”) (142 g). The THF was then cooled in thereactor to −78° C. The contents of the reactor were then titrated with a0.36 M solution of sec-butyllithium in cyclohexane until the contents ofthe reactor exhibited a persistent pale yellow color. The contents ofthe reactor were then warmed to, and maintained at, 30° C. until thecolor of the contents completely disappeared (approximately 10-15minutes). 1,1-diphenylethylene (0.086 g) diluted in cyclohexane (1.63 g)was then transferred to the reactor via cannula. The contents of thereactor were then cooled to −78° C. Sec-butyllithium (4.5 g) dilutedwith cyclohexane to concentration of 0.065 M was then rapidly added tothe reactor via cannula, causing the reactor contents to turn a darkruby red. The reactor contents were allowed to stir for 21 minutes. Thenmethyl methacrylate (11.5 g) in cyclohexane (17.81 g) was transferred tothe reactor via cannula, causing the color of the reactor contents todisappear. The reactor contents exhibited a 15-20° C. temperature risewithin 1 minute of the addition of the methyl methacrylate to thereactor. The contents of the reactor then cooled back down to −78° C.and the reactor contents were stirred for an additional 30 minutes. Asmall portion of the reactor contents was then withdrawn for gelpermeation chromatography analysis of the polymethyl methacrylate(“PMMA”) block formed. (Trimethylsilyl) methyl methacrylate (“TMSMMA”)(4.27 g) diluted in cyclohexane (10.26 g) was then transferred into thereactor via cannula. Within 2 minutes of the addition of the TMSMMA tothe reactor, the reactor contents warmed to −70° C. before cooling backdown to −78° C. The reactor contents were stirred for an additional 3.75hours, after which the reaction was quenched by the addition ofanhydrous methanol to the reactor. The reactor contents were thenprecipitated into 1 liter of methanol. The product solids were collectedby vacuum filtration. After washing with additional methanol, thepolymer was redissolved in 150 mL of methylene chloride, washed twicewith deionized water and then reprecipitated into 1 liter of methanol.The polymer was then filtered and dried overnight in a vacuum oven at60° C., yielding 15.1 g. The product poly(methylmethacrylate)-b-poly(trimethylsilyl) methyl methacrylate block copolymer(“PMMA-b-PTMSMMA”) exhibited a weight average molecular weight, M_(W),of 42.0 kg/mol; a polydispersity, PD, of 1.18 and a 28 wt %poly(trimethylsilyl)methyl methacrylate content (as determined by ¹HNMR).

Example 4 Substrate Preparation

Substrates were prepared by cutting pieces (˜1″×1″) from a silicon waferhaving a native oxide layer. A hydroxyl-terminated polystyrene brushprepared according to Example 1 was dissolved in toluene to form 1.5 wt% brush solution. The brush solution was then spin coated onto eachsubstrate at 3,000 rpm for 1 minute. The deposited brush layer was thenbaked by placing the substrate onto a hotplate set at 150° C. for 1minute. The deposited brush layer was then annealed by placing thesubstrate onto another hotplate set at 250° C. for 20 minutes in anitrogen atmosphere. The substrate was then cooled to room temperature.The substrate was then immersed in toluene for 1 minute. The substratewas then spun dry at 3,000 rpm for 1 minute. The substrate was thenplaced on a hotplate set at 110° C. for 1 minute and then stored innitrogen until used.

Comparative Example F1 Film Deposition-Self Assembly

A PS-b-PDMS block copolymer prepared according to Comparative Example C1was dissolved in propylene glycol methyl ether acetate(“PGMEA”)(Dowanol® PMA available from The Dow Chemical Company) to forma 1.6 wt % solution. The solution was then hand filtered through a 0.2μm Whatman syringe filter. The filtered solution was then spin coatedonto the polystyrene brushed surface of a substrate prepared accordingto Example 4 at 2,370 rpm to form a 41.5 nm PS-b-PDMS film. Thesubstrate was then placed on a hotplate set at 150° C. for 1 minute tobake the film. The substrate was then placed on another hotplate set at250° C. for 1 hour under 50 psig nitrogen to anneal the PS-b-PDMS film.

A surface wetting layer of PDMS formed on the annealed film at theatmosphere-film interface. The annealed film was then treated using twoconsecutive reactive ion etching (RIE) steps to reveal the blockcopolymer morphology of the deposited PS-b-PDMS film. First, a short CF₄plasma (10 mT, 50 W) RIE treatment (8 seconds post plasma stabilization)was used to punch through the surface wetting layer of PDMS. Then, an O₂plasma RIE treatment (25 seconds post plasma stabilization) was employedto remove the polystyrene domains and convert the PDMS domains toSiO_(x).

The plasma treated film was then examined by Scanning ElectronMicroscopy using a Hitachi S-4500 scanning electron microscope (SEM)with a secondary electron detector. The test sample was mounted on theSEM stage using double sided carbon tape and cleaned by blowing nitrogenprior to analysis. An image of the test sample was collected at 50,000×magnification and working distances between 4 and 8. The film exhibiteda pitch of 32.0 nm.

Comparative Example F2 Film Deposition-Self Assembly

A PMMA-b-PTMSMMA block copolymer prepared according to Example 2 wasdissolved in propylene glycol methyl ether acetate (PGMEA) to form a 1.2wt % solution. The solution was then hand filtered through a 0.2 μmWhatman syringe filter. The filtered solution was then spin coated ontoa polystyrene brushed surface of a substrate prepared according toExample 4 to form a PMMA-b-PTMSMMA film. The substrate was then placedon a hotplate set at 150° C. for 1 minute to bake the film. Thesubstrate was then placed on another hotplate set at 290° C. under airfor 2 min.

A surface wetting layer of PTMSMMA formed on the annealed film at theatmosphere-film interface. The annealed film was then treated using twoconsecutive reactive ion etching (RIE) steps to reveal the blockcopolymer morphology of the deposited PMMA-b-PTMSMMA film. First, ashort CF₄ plasma (10 mT, 50 W) RIE treatment (8 seconds post plasmastabilization) was used to punch through the surface wetting layer ofPTMSMMA. Then, an O₂ plasma RIE treatment (25 seconds post plasmastabilization) was employed to remove the poly(methyl methacrylate)domains and converting the PTMSMMA domains to SiO_(x).

The plasma treated product film was then examined by Scanning ElectronMicroscopy using a Hitachi S-4500 scanning electron microscope (SEM)with a secondary electron detector. The test sample was mounted on theSEM stage using double sided carbon tape and cleaned by blowing nitrogenprior to analysis. An image of the test sample was collected at 50,000×magnification and working distances between 4 and 8. The product filmexhibited a pitch of 36.3 nm.

Example 5 Film Deposition-Self Assembly

A formulation of PMMA-b-PTMSMMA block copolymer prepared according toExample 2 and 5 wt % of the antioxidant pentaerythritoltetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (Availablefrom BASF under the tradename IRGANOX® 1010) was dissolved in propyleneglycol methyl ether acetate (PGMEA) to form a 1.2 wt % solution. Thesolution was then hand filtered through a 0.2 μm Whatman syringe filter.The filtered solution was then spin coated onto a polystyrene brushedsurface of a substrate prepared according to Example 4 to form aPMMA-b-PTMSMMA film. The substrate was then placed on a hotplate set at150° C. for 1 minute to bake the film. The substrate was then placed onanother hotplate set at 290° C. under air for 2 min.

A surface wetting layer of PTMSMMA formed on the annealed film at theatmosphere-film interface. The annealed film was then treated using twoconsecutive reactive ion etching (RIE) steps to reveal the blockcopolymer morphology of the deposited PMMA-b-PTMSMMA film. First, ashort CF₄ plasma (10 mT, 50 W) RIE treatment (8 seconds post plasmastabilization) was used to punch through the surface wetting layer ofPTMSMMA. Then, an O₂ plasma RIE treatment (25 seconds post plasmastabilization) was employed to remove the poly(methyl methacrylate)domains and converting the PTMSMMA domains to SiO_(x).

The plasma treated product film was then examined by Scanning ElectronMicroscopy using a Hitachi S-4500 scanning electron microscope (SEM)with a secondary electron detector. The test sample was mounted on theSEM stage using double sided carbon tape and cleaned by blowing nitrogenprior to analysis. An image of the test sample was collected at 50,000×magnification and working distances between 4 and 8. The product filmexhibited a pitch of 35.7 nm with no apparent, detrimental effects fromthe elevated antioxidant concentration.

We claim:
 1. A copolymer composition, comprising: a block copolymerhaving a poly(acrylate) block and a poly(silyl acrylate) block; and, anantioxidant; wherein the block copolymer exhibits a number averagemolecular weight, M_(N), of 1 to 1,000 kg/mol; wherein the copolymercomposition contains ≧2 wt % antioxidant (based on the weight of theblock copolymer) and, wherein the block copolymer exhibits apolydispersity, PD, of 1 to
 2. 2. The copolymer composition of claim 1,wherein the copolymer composition contains 5 to 30 wt % antioxidant(based on the weight of the block copolymer).
 3. The copolymercomposition of claim 1, wherein the antioxidant is selected from thegroup consisting of: an antioxidant containing at least one2,6-di-tert-butylphenol moiety; an antioxidant containing at least onemoiety according to the formula

an antioxidant containing at least one moiety according to the formula

an antioxidants containing at least one moiety according to the formula

mixtures thereof.
 4. The copolymer composition of claim 1, wherein theantioxidant is selected from the group consisting of

mixtures thereof.
 5. The copolymer composition of claim 1, wherein thepoly(acrylate) block includes residues from at least one of an acrylatemonomer, a deuterated acrylate monomer, an acrylate block modifyingmonomer and a deuterated acrylate block modifying monomer; wherein thepoly(acrylate) block includes >75 wt % of acrylate monomer derivedunits; wherein the acrylate monomer is selected from the groupconsisting of C₆₋₁₄ aryl (C₁₋₅ alkyl)acrylate; C₁₋₅ alkyl (C₁₋₅alkyl)acrylate; wherein the deuterated acrylate monomer is selected fromthe group consisting of deuterated C₆₋₁₄ aryl (C₁₋₅ alkyl)acrylate;deuterated C₁₋₅ alkyl (C₁₋₅ alkyl)acrylate; wherein the acrylate blockmodifying monomer is selected from the group consisting of a C₁₋₅ alkeneand a C₃₋₇ cycloalkene; wherein the deuterated acrylate block modifyingmonomer is selected from a deuterated C₁₋₅ alkene and deuterated a C₃₋₇cycloalkene; and, wherein the poly(silyl acrylate) block includesresidues from at least one of a silyl acrylate monomer, a deuteratedsilyl acrylate monomer, a silyl acrylate block modifying monomer and adeuterated silyl acrylate block modifying monomer; wherein thepoly(silyl acrylate) block includes >75 wt % silyl acrylate monomerderived units; wherein the silyl acrylate monomer is according to thefollowing formula(R¹)(R²)(R³)Si)_(r)R⁴ _(x)OOCC(R⁵)═CR⁶ ₂ wherein each R¹, R² and R³ isindependently selected from the group consisting of a C₁₋₆ alkyl group,a silylated C₁₋₆ alkyl group, an oxy C₁₋₆ alkyl group, an oxy silylatedC₁₋₆ alkyl group, a C₆₋₁₀ aryl group, an oxy C₆₋₁₀ aryl group, asilylated C₆₋₁₀ aryl group, an oxy silylated C₆₋₁₀ aryl group, a C₁₋₁₀arylalkyl group, an oxy C₁₋₁₀ arylalkyl group, a silylated C₁₋₁₀arylalkyl group, an oxy silylated C₁₋₁₀ arylalkyl group, a C₆₋₁₀alkylaryl group, an oxy C₆₋₁₀ alkylaryl group, a silylated C₆₋₁₀alkylaryl group, an oxy silylated C₆₋₁₀ alkylaryl group; wherein r isselected from the group consisting of 0, 1, 2 and 3; wherein R⁴ isselected from the group consisting of a C₁₋₃ alkyl; wherein x isselected from the group consisting of 0 and 1; wherein R⁵ is selectedfrom the group consisting of a hydrogen and a methyl group; wherein eachR⁶ is a hydrogen; wherein the silyl acrylate monomer includes at leastone Si atom; wherein the deuterated silyl acrylate monomer is accordingto the following formula(R⁷(R⁸)(R⁹)Si)_(t)R¹⁰ _(y)OOCC(R¹¹)═CR¹² ₂ wherein each R⁷, R⁸ and R⁹ isindependently selected from a C₁₋₆ alkyl group, a silylated C₁₋₆ alkylgroup, an oxy C₁₋₆ alkyl group, an oxy silylated C₁₋₆ alkyl group, aC₆₋₁₀ aryl group, an oxy C₆₋₁₀ aryl group, a silylated C₆₋₁₀ aryl group,an oxy silylated C₆₋₁₀ aryl group, a C₁₋₁₀ arylalkyl group, an oxy C₁₋₁₀arylalkyl group, a silylated C₁₋₁₀ arylalkyl group, an oxy silylatedC₁₋₁₀ arylalkyl group, a C₆₋₁₀ alkylaryl group, an oxy C₆₋₁₀ alkylarylgroup, a silylated C₆₋₁₀ alkylaryl group, an oxy silylated C₆₋₁₀alkylaryl group, a deuterated C₁₋₆ alkyl group, a deuterated silylatedC₁₋₆ alkyl group, a deuterated oxy C₁₋₆ alkyl group, a deuterated oxysilylated C₁₋₆ alkyl group, a deuterated C₆₋₁₀ aryl group, a deuteratedoxy C₆₋₁₀ aryl group, a deuterated silylated C₆₋₁₀ aryl group, adeuterated oxy silylated C₆₋₁₀ aryl group, a deuterated C₁₋₁₀ arylalkylgroup, a deuterated oxy C₁₋₁₀ arylalkyl group, a deuterated silylatedC₁₋₁₀ arylalkyl group, a deuterated oxy silylated C₁₋₁₀ arylalkyl group,a deuterated C₆₋₁₀ alkylaryl group, a deuterated oxy C₆₋₁₀ alkylarylgroup, a deuterated silylated C₆₋₁₀ alkylaryl group and a deuterated oxysilylated C₆₋₁₀ alkylaryl group; wherein t is selected from the groupconsisting of 0, 1, 2 and 3; wherein R¹⁰ is selected from the groupconsisting of a C₁₋₃ alkyl group, and a deuterated C₁₋₃ alkyl; wherein yis 0 or 1; wherein R¹¹ is selected from the group consisting of ahydrogen, a deuterium, a methyl group and a deuterated methyl group;wherein each R¹² is selected from a hydrogen and a deuterium; whereinthe deuterated silyl acrylate monomer contains at least one Si atom;and, wherein the deuterated silyl acrylate monomer contains at least onedeuterium; wherein the silyl acrylate block modifying monomer isselected from the group consisting of an alkene and a cycloalkene; and,wherein the deuterated silyl acrylate block modifying monomer isselected from the group consisting of a deuterated alkene and adeuterated cycloalkene.
 6. The copolymer composition of claim 5, whereinthe copolymer composition contains 5 to 30 wt % antioxidant (based onthe weight of the block copolymer).
 7. The copolymer composition ofclaim 5, wherein the acrylate monomer is selected from the groupconsisting of butyl (meth)acrylate, propyl (meth)acrylate), ethyl(meth)acrylate, methyl (meth)acrylate; wherein the deuterated acrylatemonomer is selected from the group consisting of deuterated butyl(meth)acrylate, deuterated propyl (meth)acrylate), deuterated ethyl(meth)acrylate, deuterated methyl (meth)acrylate; wherein the acrylateblock modifying monomer is ethylene; and, wherein the deuteratedacrylate block modifying monomer is deuterated ethylene; and, whereinthe silyl acrylate monomer is selected from the group consisting of(trimethylsilyl)methyl (meth)acrylate, (triethylsilyl)methyl(meth)acrylate, (tripropylsilyl)methyl (meth)acrylate,(triisopropylsilyl)methyl (meth)acrylate, (tributylsilyl)methyl(meth)acrylate, (tri-sec-butylsilyl)methyl (meth)acrylate,(triisobutylsilyl)methyl (meth)acrylate, (sec-butylmethylsilyl)methyl(meth)acrylate, (sec-butyldimethylsilyl)methyl (meth)acrylate,(dimethylpropylsilyl)methyl (meth)acrylate,(monomethyldipropylsilyl)methyl (meth)acrylate,(methylethylpropylsilyl)methyl (meth)acrylate, bis(trimethylsilyl)methyl(meth)acrylate, tris(trimethylsilyl)methyl (meth)acrylate,(pentamethyldisilyl)methyl (meth)acrylate, tris(trimethylsiloxy)methyl(meth)acrylate, tris(trimethylsiloxy)propyl (meth)acrylate),(pentamethyldisiloxy)methyl (meth)acrylate, (pentamethyldisiloxy)propyl(meth)acrylate, (trimethoxysilyl)propyl (meth)acrylate and(triethoxysilyl)propyl (meth)acrylate; wherein the deuterated silylacrylate monomer is selected from the group consisting of deuterated(trimethylsilyl)methyl (meth)acrylate, deuterated (triethylsilyl)methyl(meth)acrylate, deuterated (tripropylsilyl)methyl (meth)acrylate,deuterated (triisopropylsilyl)methyl (meth)acrylate, deuterated(tributylsilyl)methyl (meth)acrylate, deuterated(tri-sec-butylsilyl)methyl (meth)acrylate, deuterated(triisobutylsilyl)methyl (meth)acrylate, deuterated(sec-butylmethylsilyl)methyl (meth)acrylate, deuterated(sec-butyldimethylsilyl)methyl (meth)acrylate, deuterated(dimethylpropylsilyl)methyl (meth)acrylate, deuterated(monomethyldipropylsilyl)methyl (meth)acrylate, deuterated(methylethylpropylsilyl)methyl (meth)acrylate, deuteratedbis(trimethylsilyl)methyl (meth)acrylate, deuteratedtris(trimethylsilyl)methyl (meth)acrylate, deuterated(pentamethyldisilyl)methyl (meth)acrylate, deuteratedtris(trimethylsiloxy)methyl (meth)acrylate, deuteratedtris(trimethylsiloxy)propyl (meth)acrylate), deuterated(pentamethyldisiloxy)methyl (meth)acrylate, deuterated(pentamethyldisoloxy)propyl (meth)acrylate, deuterated(trimethoxysilyl)propyl (meth)acrylate and deuterated(triethoxysilyl)propyl (meth)acrylate; wherein silyl acrylate blockmodifying monomer is ethylene; and, wherein the deuterated silylacrylate block modifying monomer is selected from a deuterated ethylene.8. The copolymer composition of claim 7, wherein the poly(acrylate)block includes >95 wt % of acrylate monomer derived units, wherein theacrylate monomer is methyl (meth)acrylate; and, wherein the poly(silylacrylate) block includes >95 wt % of silyl acrylate monomer derivedunits, wherein the silyl acrylate monomer is (trimethylsilyl)methylmethacrylate.
 9. The copolymer composition of claim 8, wherein thecopolymer composition contains 5 to 30 wt % antioxidant (based on theweight of the block copolymer).
 10. A method comprising: providing asubstrate; providing a copolymer composition according to claim 1;applying a film of the copolymer composition to the substrate;optionally, baking the film; annealing the film, leaving a pattern ofpoly(acrylate) domains and poly(silyl acrylate) domains; treating theannealed film to remove the poly(acrylate) domains from the annealedfilm and to convert the poly(silyl acrylate) domains in the annealedfilm to SiO_(x).
 11. A copolymer composition, comprising: a blockcopolymer having a poly(acrylate) block and a poly(silyl acrylate)block; wherein the block copolymer exhibits a number average molecularweight, M_(N), of 1 to 1,000 kg/mol; wherein the block copolymerexhibits a polydispersity, PD, of 1 to 2; and, wherein the blockcopolymer contains ≦75 wt % of a poly(methylmethacrylate)-block-poly((trimethylsilyl)methyl methacrylate) diblockcopolymer.
 12. The copolymer composition of claim 11, wherein the blockcopolymer contains <0.001 wt % of a poly(methylmethacrylate)-block-poly((trimethylsilyl)methyl methacrylate) diblockcopolymer.